Composition of matter



Patented Dec. 31,1340

PATENT DFFICE COLIPOSITION OF MATTER Leo Wallerstein, New York, N. Y., and Julius Pfannmuller, North Plainfield, N. J., assignors to Wallerstein Company, Inc., New York, N Y.,

a corporation of New York No Drawing. Application July 27,1938.

Serial No. 221,643

5 Claims. This invention relates to a composition of matter and more particularly to a composition of matter for use in unhairing skins and hides.

Before hides and skins can be converted into leather the hair must be removed. This is nor mally accomplished by a chemical treatment for loosening the hair, followed by a mechanical removal of the loosened hair. A commonly used process of unhairing involves the use of a lime bath. For many years, so-called sharpeners, such as sodium sulphide, red arsenic and certain amines have been added to the lime bath. If such sharpeners are not used, the unhairing operation involves a length of time that is inconvenient and expensive. on the other hand, most of these sharpeners attack the hair. As a result, the hair, which may be a valuable by-product, is either totally destroyed or is recovered in a more or less 20 damaged condition. I 1 It has recently been proposed to avoid this dilemma by adding to the lime bath a relatively small amount of sodium hydrosulphite (Na2ScO4) or similar materials. It has been found that with such a bath, hair loosening is more rapidly-10btained than with lime alone and the hair is not attacked.

It is known that sodium hydrosulphite deterifs' crates when exposed for any considerable timto' 30 moist air.

matter, be prevented from leaving open to the air, the bins or other containers for the materials used. As beamhouseshave notoriously damp or 35 moist atmospheres, it follows that supplies of sodium hydrosulphite, on hand for unhairing baths, are exposed to moist air and soon deteriorate;

It is an object of the present invention to provide a composition of matter containing sodium 4 hydrosulphite, such that the latter ingredient is stabilized or protected to a substantial degree against deterioration from exposure to moist air. In carrying out the invention, we combine with sodium hydrosulphite (NazSzOr) one or more ma- 45 terials which stabilize or tend to stabilize the hydrosulphite against the efiects of damp air and which, at the same time, have no detrimental eifect in the unhairing bath.

One material we have found suitable for this 50 purpose is anhydrous sodium sulphite. In carrying out the. invention to what is now considered the best advantage, we also add a relatively small amount of calcium oxide (unslaked lime).

55 While the proportionsv of the several ingredients It has been observed that tannry workmen cannot, as a rule and as a practical may vary, the following proportions (by weight) have been found to 'give satisfactory results:

, Per cent Sodium-hydrosulphite 50 6 Anhydrous sodium sulphite c .l 40-45 Calcium oxide a -10 In preparing the composition of matter above described, the materials referred to are mixed together, in dry conditiomin any suitable manner, 10

v as by means of mechanical mixers. The mixture is then preferably packed and shipped in moisture-proof containers.

With the mixture described, the sodium hydro.-

sulphite is well protected against the effects of moist and damp air, at least over any normal period during which the mixture is likely to be stored awaiting use. It follows that deterioration of the hydrosulphite is substantially lessened even 1 though workmen in the beamhouse at times leave the cover or lid off the container. Moreover, neither the sodium sulphite nor the calcium oxide have any detrimental efiect or. the unhairing operation when added to the lime bath.

The calcium oxide, when the mixture is added to the bath, merely increases the lime content of v [the bath by an insignificant amount. It is recognized that the use of sodium sulphite as an unhairing agent has been proposed. The sulphite in the present composition, however, is not added for that purpose but only as a stabilizing agent for the sodium hydrosulphite. In the amounts of the mixture normally used and in the time the skins or hides are kept in the bath when sodium hydrosulphite is used, there is substantially no unhairing action due to the sulphite. In fact, a proper amount of sodium hydrosulphite for a given unhairing bath having been predetermined, the present composition is normally used in such amounts as to give the same quantity of hydrosulphite for that bath. That is to say, if a formula calls, say, for 25 pounds of sodium hydrosulphite and if the mixture here described contains 50% hydrosulphite, 50 pounds of the mixture is used. Thus, as far as the unhairing action is concerned, the calcium oxide and the sodium sulphite may be considered as inert ingredients. I 4 The composition of the present invention has a further advantage. Ordinary beamhouse workmen cannot, as a rule, be depended on to weigh out accurately materials used in the wet process. But since, under normal conditions, the greater the bulk, the less the coefiicient of error, with 'a mixture such as that described, containing for example, 50% of hydrosulphite, any error in measuring doses to be added to the bath will, as far as the hydrosulphite content is concerned, he reduced by half. The mixture, therefore, tends to make beamhouse operations more nearly "foolproof.

Other materials may be substituted for the anhydrous sodium sulphite, for example, anhydrous sodium sulphate.

While the composition described is particularly useful in connection with unhairing operations, it may also be used in other connections where it is desired to protect sodium hydrosulphite against the effects of moist air.

What is claimed is:

1. A composition of matter for use in unhairing baths for skins and hides, comprising sodium hydrosulphite and anhydrous sodium sulphite.

2. A composition of matter for use in unhairing baths for skins and hides, comprising sodium hydrosulphite, anhydrous sodium sulphite and calcium oxide.

Per cent Sodium hydrosulphite 50 Anhydrous sodium sulphite 40-45 Calcium oxide 5-10 5. A composition of matter for use in unhairing baths for skins and hides, comprising sodium hydrosulphite and a material selected from the group consisting of anhydrous sodium sulphite and anhydrous sodium sulphate.

LEO WALLERSTEIN. JULIUS PFANNMULLER. 

